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Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. [4] It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk.
0.1 × ( 12 ÷ 8 ) = 0.15 grain per dscf when corrected to a gas having a specified reference CO 2 content of 12 volume %. Notes: Although ppmv and grains per dscf have been used in the above examples, concentrations such as ppbv (i.e., parts per billion by volume), volume percent, grams per dscm and many others may also be used.
A gypsum block is made of gypsum plaster and water. The manufacturing process [1] is automated at production plants where raw gypsum (CaSO 4 ·2H 2 O) is ground and dried, then heated to remove three-quarters of the bound water and thus transformed into calcium sulfate hemihydrate (CaSO 4 ·½H 2 O), also known as gypsum plaster, stucco, calcined gypsum or plaster of Paris.
With judicious heating, gypsum converts to the partially dehydrated mineral called bassanite or plaster of Paris. This material has the formula CaSO 4 ·( n H 2 O), where 0.5 ≤ n ≤ 0.8. [ 8 ] Temperatures between 100 and 150 °C (212–302 °F) are required to drive off the water within its structure.
Ra, this limit is equivalent to 0.01 milligrams (0.00015 gr) of radium per metric ton or a concentration of 10 parts per trillion. (See § Gyp stacks below.) EPA approved the use of phosphogypsum for road construction during the Trump Administration in 2020, saying that the approval came at the request of The Fertilizer Institute, which ...
where TDS is expressed in mg/L and EC is the electrical conductivity in microsiemens per centimeter at 25 °C. The conversion factor k e varies between 0.55 and 0.8. [5] Some TDS meters use an electrical conductivity measurement to the ppm using the above formula. Regarding units, 1 ppm indicates 1 mg of dissolved solids per 1,000 g of water. [6]
Plaster was first used as a building material and for decoration in the Middle East at least 7,000 years ago. In Egypt, gypsum was burned in open fires, crushed into powder, and mixed with water to create plaster, used as a mortar between the blocks of pyramids and to provide a smooth wall facing.
2 mg/kg 2 parts per million 2 ppm 2 × 10 −6: A mass fraction of... 2 μg/kg 2 parts per billion ! 2 ppb ! 2 × 10 −9: A mass fraction of... 2 ng/kg 2 parts per trillion ! 2 ppt ! 2 × 10 −12: A mass fraction of... 2 pg/kg 2 parts per quadrillion ! 2 ppq ! 2 × 10 −15: A volume fraction of... 5.2 μL/L 5.2 parts per million 5.2 ppm 5.2 ...